How to generate single reusable random password with ansible

Question

That is to say: How to evaluate the password lookup only once?

- name: Demo
  hosts: localhost
  gather_facts: False
  vars:
    my_pass: "{{ lookup('password', '/dev/null length=15 chars=ascii_letters') }}"
  tasks:
  - debug:
      msg: "{{ my_pass }}"
  - debug:
      msg: "{{ my_pass }}"
  - debug:
      msg: "{{ my_pass }}"

each debug statement will print out a different value, e.g:

PLAY [Demo] *************

TASK [debug] ************
ok: [localhost] => {
    "msg": "ZfyzacMsqZaYqwW"
}

TASK [debug] ************
ok: [localhost] => {
    "msg": "mKcfRedImqxgXnE"
}

TASK [debug] ************
ok: [localhost] => {
    "msg": "POpqMQoJWTiDpEW"
}

PLAY RECAP ************
localhost                  : ok=3    changed=0    unreachable=0    failed=0   

ansible 2.3.2.0

Answer 1

Use set_fact to assign permanent fact:

- name: Demo
  hosts: localhost
  gather_facts: False
  vars:
    pwd_alias: "{{ lookup('password', '/dev/null length=15 chars=ascii_letters') }}"
  tasks:
    - set_fact:
        my_pass: "{{ pwd_alias }}"
    - debug:
        msg: "{{ my_pass }}"
    - debug:
        msg: "{{ my_pass }}"
    - debug:
        msg: "{{ my_pass }}"

Answer 2

I've been doing it this way and never had an issue.

- name: Demo
  hosts: localhost
  gather_facts: False 

  tasks:
   - set_fact:
       my_pass: "{{ lookup('password', '/dev/null length=15 chars=ascii_letters') }}"
   - debug:
       msg: "{{ my_pass }}"